[1] Georgetown Univ, Med Ctr, Drug Discovery Program, Washington, DC 20007 USA
[2] Georgetown Univ, Med Ctr, Dept Neurol, Washington, DC 20007 USA
[3] Georgetown Univ, Med Ctr, Dept Oncol, Washington, DC 20007 USA
[4] Georgetown Univ, Med Ctr, Dept Neurosci, Washington, DC 20007 USA
[5] Univ Texas, Med Branch, Dept Pharmacol & Toxicol, Galveston, TX 77555 USA